Kara Watson explores the enigma of the newly discovered fish-scale gecko, that can instantly remove its scales on demand
Last week, a new species of fish-scale geckos was discovered for the first time in 75 years. Geckolepis megalepis was described accurately for the first time, having been previously confused with another closely-related species. Identifying these geckos is made especially difficult, given that they can pull their skin off at will.
Fish-scale geckos have large scales that are very like bony plates, and G. megalepis has the largest scales of any gecko. The size of the scales allows them to be easily torn from the skin, splitting along a specialised layer of cells known as the “tear zone”. The species is particularly sensitive to shedding their scales, doing so at the slightest touch, and leaving their muscle exposed. They then retreat to a safe location, where they can grow back their scales within a matter weeks.
It is thought that larger scales give an increased surface area relative to the attachment area. This allows the larger scales to be removed with much less force than would be needed for detachment of smaller scales, which is what allows this reptile discard it’s skin with such ease. They even constrict their blood vessels during the shedding process to avoid any bleeding while their skin is removed.
As the slippery geckos are for obvious reasons, difficult to catch in tact, several methods were devised to capture them. Often, lots of cotton wool was used to delicately pick them up, or sometimes they could be lured into a bag to avoid touching them. Although G. megalepis was previously hard to distinguish from other species of fish-scale geckos, one of the main ways of differentiate reptile species is to look at the scale pattern. This is almost impossible when your study subjects have discarded their scales so many times that they have lost any discernible pattern.
To get around this, the researchers use micro-computed tomography, which allows them to create a 3D x-ray image of the geckos skeleton. They used this to identify differences in their skulls that separated them from other fish-scale gecko species.
Fish-scale geckos are found in Madagascar, and are under threat from nearby mining operations and habitat loss. Therefore, even though they’ve just been found, one of the study authors, Mark Scherz, recommended that they be listed as near threatened. Hopefully these delightfully gross reptiles will be studied further, so we can learn more about them.